1. Field of the Invention
The present invention relates to a camera including a line-of-sight detecting apparatus for detecting a line of sight of an observer.
2. Description of the Related Art
There have been proposed a wide variety of apparatuses for detecting a position at which the observer gazes on a viewing plane, i.e., a so-called a line of sight (visual axis). A method of detecting the line of sight in, e.g., U.S. patent application Ser. No. 003,954 involves the steps of projecting a parallel light from a light source on a front part of the observer's eyeball and thus obtaining the visual axis from the cornea reflection image of the reflected light from the cornea and an imaging position of the pupil.
Further, there have been made some proposals in which a photometric mode for determining an auto exposure of the camera by using line-of-sight information of the observer is changed. According to U.S. patent application Ser. No. 958,482, the line of sight of the observer is detected, and a photometric value is varied corresponding to a state of distribution of eye-gazing points (target positions). Concretely, the center priority average photometry and the spot photometry are selected. In addition, there has been a proposal in which the observer's line of sight is detected, one or more areas are selected from a plurality of partitioned areas by using the line-of-sight information, and luminances of the selected areas are weight-averaged to obtain a photometric value.
Moreover, there have been also proposed multiple photometric apparatuses constructed to give a proper exposure to the photographing picture by outputting and using a plurality of luminance signals of a plurality of respective areas into which the field is partitioned. However, there exist a comparatively small number of proposals of photometric apparatuses for accurately judging whether or not a flash of light should be emitted.
According to U.S. patent application Ser. No. 646,248, there is proposed a photometric apparatus in a camera having focus detecting means so constructed as to be capable of detecting focal points of a plurality of areas within the photographing picture. The photometric apparatus comprises light receiving means for detecting luminances of a plurality of subareas into which the field is partitioned and detection area selecting means for selecting one of the plurality of focus detection areas. Information on a luminance of the subarea including the focus detection area selected by the focus detecting means is compared with information on a maximum luminance in the plurality of subareas, thereby determining whether the flash of light is emitted or not.
However, the following problems arise. In the above proposals, the luminance information of the subarea including the focus detection area is determined by the plurality of focus detecting means. The luminance of the principal subject intended by the photographer is not necessarily measured. That is, the algorithm for determining a focus detecting position is employed in the focus detecting means so constructed as to be capable of detecting the focal points of the plurality of areas within the photographing picture. This algorithm generally takes a so-called near priority mode in which a subject closest to the camera is defined as a principal photographing subject in terms of probability. Hence, if the photographer takes a shot of an object as the principal subject other than the closest object within the photographing picture, a problem is that the condition for emitting the flash of light is not well judged.
A large number of cameras in a detecting system have hitherto been proposed, the arrangement being such that the flash of light is emitted toward the subject, and a quantity of light emitted is determined corresponding to an intensity (light quantity) of the reflected light after detecting the reflected light from the subject. In the majority of those cameras, however, the photometry is effected in concentration on the center of the picture by means of a single piece of photometric (detecting) sensor. For this reason, if the principal subject is relatively small on the picture or in a position off the center of the picture, the photometric sensor undergoes an influence from the background. This results in such a problem that a proper quantity of light cannot be obtained.
Further, a proposal against the above-mentioned problems has been made in U.S. Pat. No. 5,111,231 by the present applicant. Provided is a focus detecting means for obtaining focus detection information of areas corresponding to a plurality of detecting areas. Output information of each detecting area is evaluated based on focus information of each area which is given from the focus detecting means. A flash emitting quantity is controlled.